This invention is directed to certain novel magnesium dialkoxides and to complexes thereof and to processes for the preparation thereof.
In recent years, certain alkylmagnesium alkoxides and magnesium dialkoxides have been found to possess utility as precursors for magnesium chloride support materials utilized in the preparation of Ziegler-Natta catalysts for alpha-olefin polymerization.
For example, ethylene has been polymerized at 80.degree. C. in hexane using a magnesium alcoholate-TiCl.sub.4 reaction product (MgCl.sub.2) and a trialkylaluminum as the catalyst system. (M. Bahadir, S. Lutze, W. Payer, P. Schneller, Ger. Offen. DE No. 3,120,186, Dec. 9, 1982, to Ruhrchemie.). In another application, solid magnesium diethoxide, suspended in carbon tetrachloride, is treated with ethyl benzoate and titanium tetrachloride, and the resulting solid product is used in combination with trialkylaluminum and p-methoxybenzoate as a catalyst to polymerize propylene (B. L. Goodall, A. vander Nat, and W. Sjardyn, U.S. Pat. No. 4,414,132, to Shell Oil Co.; also U.S. Pat. No. 4,216,383).
Certain alkylmagnesium alkoxides and magnesium dialkoxides have also been generated by reaction of complexed magnesium dialkyls, coated on an inert support material, with certain alcohols. These supported magnesium dialkoxides are then further reacted with HCl and/or titanium tetrachloride to give a supported magnesium chloride catalyst which can be dried and used to polymerize ethylene (R. Hoff, U.S. Pat. No. 4,402,861; R. A. Dombro, U.S. Pat. No. 4,378,304, to Chemplex Co.; and M. Bahadir and W. Payer, Ger. Offen. DE No. 3,223,331, to Ruhrchemie.).
In still another application, a mixture of magnesium isopropoxides and aluminum isopropoxides in tetrahydrofuran (THF) (the solubility, if any, unspecified) is reacted with a solution of magnesium aluminum hydride in tetrahydrofuran to give a solution of magnesium aluminum isopropoxy hydride in THF. (S. Cucinella and G. Dozzi, Ger. Offen. DE No. 3,000,490, July 31, 1980, to Anic, Sp.A.).
Schell (U.S. Pat. No. 4,419,269) claims treating R.sub.2 Mg.multidot.xMR'.sub.x with alcohols of the general type R(OR').sub.n OH and Z(OR').sub.n (OR").sub.n, in the presence of Al(R.sup.3).sub.3 X.sub.m, but gives no examples, for instance, of the use of ethoxyethanol, and also not in the absence of aluminum compounds.
D. Gessell (U.S. Pat. Nos. 4,246,383; 4,387,200; 4,244,838; and 4,496,660 to Dow Chemical Company) also describes the preparation of useful alpha-olefin polymerization catalysts by reacting a dialkymagnesium compound (in the presence of at least 50 mole % of a trialkylaluminum compound) with sufficient n-propyl alcohol to convert all of the alkyl groups to n-propoxy groups, thus forming a hydrocarbon-soluble solution of magnesium and aluminum n-propoxides, followed by reaction of the resulting solution with a titanium ester and a chlorinating agent, ethylaluminum dichloride, to give a MgCl.sub.2 -supported titanium catalyst.
It is also known to employ a mixture of certain dialkylmagnesiums and either lithium alkoxide, sodium alkoxide, or potassium alkoxide in the polymerization and telomerization of butadiene to form low molecular weight liquid polymers, useful in the coating and also in the impregnation and encapsulation of electrical transformers and other metal parts to protect them from corrosion (C. W. Kamienski and J. F. Eastham, U.S. Pat. Nos. 3,742,077; 3,822,219; 3,847,833). Other patents describing the formation of polymeric products from similar catalyst systems are U.S. Pat. Nos. 4,139,490 and 4,429,090 (to Firestone Tire & Rubber Co.); and U.S. Pat. No. 3,716,495 (to Phillips Petroleum Co.).
Although, certain alkymagnesium alkoxides are known to be soluble in hydrocarbon solvents, as described in U.S. Pat. Nos. 4,410,742 and 4,133,824; and by G. E. Coates, J. A. Heslop, M. E. Redwood, and D. Ridley, J. Chem. Soc., 1964, 2483 (see also B. J. Wakefield in Advances in Inorganic Chemistry and Radiochemistry, Volume ii, 1968, page 396 (Academic Press), relatively little is known about the solubility of magnesium dialkoxides in various organic solvents. It is known that both magnesium dimethoxide and diethoxide are insoluble in ethers and hydrocarbon solvents, as described in Kirk Othmer's Encyclopedia of Chemical Technology, Volume 2, page 12, 3rd Edition, John Wiley, 1978. Magnesium diisopropoxide was found by D. Bryce-Smith and B. J. Wakefield (see above) to be insoluble in methylcyclohexane, benzene and ether, and only sparingly soluble in isopropanol. Magnesium di-t-butoxide is not soluble in ethyl ether (see Coates reference, as well as D. C. Bradley in Advances in Inorganic Chemistry and Radiochemistry, Volume 15, page 265, Academic Press), and thus, presumably, would be even less soluble in hydrocarbons. Solubility of magnesium alkoxides is not improved by the addition of aluminum alkyls (B. V. Johnson, N. M. Karayannis (European Patent Application No. 95,290, to Standard Oil Company). From the general dearth of information on magnesium dialkoxides, it would appear that these materials are, generally speaking, as a class insoluble or sparingly soluble and intractable in most organic solvents, particularly hydrocarbon or chlorinated hydrocarbon solvents.
Screttas (U.S. Pat. No. 3,932,545) discloses the preparation of hydrocarbon solvent-soluble alkali metal-containing organometallic products which are prepared by reacting an organo-alkali metal compound having an alkali metal-to-carbon bond with a di(organooxy) magnesium compound in a hydrocarbon solvent to produce a reaction product which, at least in the case where the organo-alkali metal compound is, for instance, phenyllithium or cyclohexyllithium, is more soluble in the hydrocarbon solvent than the organo-alkali metal compound. Illustrative examples of the organo-alkali metal compound are n-butyllithium, cyclohexyllithium, cyclohexylsodium, phenyllithium and phenylsodium. Illustrative examples of the di(organooxy) magnesium compound are magnesium dialkoxides such as di-n-butoxy-magnesium, di(2-methoxy-ethoxy)-magnesium, and di-(2-ethoxyethoxy)-magnesium. Among its other lack of disclosure of various facets of my present invention is the absence of any teaching or concept of the production of hydrocarbon solutions prepared by reacting a dialkylmagnesium compound with aliphatic, cycloaliphatic or acyclic beta- and/or gamma-alkyl-substituted C.sub.5 -C.sub.18 secondary or tertiary alcohols, to produce magnesium dialkoxides having excellent solubility in hydrocarbon or chlorinated hydrocarbon solvents.
Aishima et al (U.S. Pat. No. 4,027,089) deals with a process of polymerizing ethylene or mixtures of ethylene and other olefins in the presence of certain catalysts, as well as with certain catalysts for use in such polymerizations. The catalysts utilized are certain hydrocarbon-soluble organoaluminum-magnesium complexes defined by a general formula which is set out, for instance, in Column 2 and claims 1 and 14 of said patent. Aishima et al recognize that, generally speaking, organomagnesium compounds are insoluble in inert hydrocarbon solvents, although certain organomagnesium compounds have heretofore been prepared which possess reasonably good solubilities in inert hydrocarbon solvents. To the extent that certain of the Aishima et al novel catalysts are of the type which comprise complexes having alkoxy groups, they comprise organoaluminum-magnesium complexes having an alkoxy group, which complexes are soluble in inert hydrocarbon solvents, and they involve reacting certain alcohols with magnesium alkyl-aluminum alkyl complexes in which the Mg/Al ratio is from 1 to 10, with a preferred range of 2 to 6. Such products are, in any event, not magnesium dialkoxides, but rather alkylaluminum alkoxides, R.sub.x Al(OR).sub. y, mixed with alkylmagnesium alkoxides, R.sub.x Mg(OR).sub.y, where R is alkyl, in which alkoxides there is more alkyl than alkoxy present (x&gt;y). These products would be expected to be considerably more soluble than the substantially pure magnesium dialkoxide products of the present invention, which may contain optionally, distinctly minor amounts of alumimum alkoxides as solubilizers, but much less than are essential and present in the complexes of the Aishima et al patent. Over and above the foregoing, in accordance with the particularly important and advantageous aspects of the present invention, only certain types of alcohols, not taught nor suggested by Aishima et al, have been found by me to produce certain novel and useful magnesium dialkoxides which are highly soluble in hydrocarbon or chlorinated hydrocarbon solvents.
Malpass et al (U.S. Pat. No. 4,133,824) discloses hydrocarbon-soluble complexes (R'.sub.2 Mg).sub.m .multidot.[(R'O).sub.2 Mg].sub.n made by reacting, for instance, a di-n-alkyl-magnesium with oxygen-containing metal compounds, illustrative of which are magnesium dialkoxides or aluminum trialkoxides. Examples are complexes of di-n-butylmagnesium in heptane with magnesium diethoxide and complexes of di-n-butylmagnesium in benzene with aluminum triisopropoxide, where the ratio of m to n is at least one or greater. As a class, generally speaking, compounds or complexes of the formula R.sub.2 Mg.multidot.(RO).sub.2 Mg or (RMgOR), where R is alkyl, are hydrocarbon-soluble. In contradistinction to what is disclosed in said Malpass et al patent, only very few and only particular types of alcohols on substantially complete reaction (n&lt;&lt;m) in R.sub.2 Mg).sub.n .multidot.((R'O).sub.2 Mg).sub.m of the alkyl groups in R.sub.2 Mg) serve to provide a hydrocarbon-soluble product without any, or without a significant quantity of, aluminum also being present, as is shown below in this aspect of the present invention.
Mueller (U.S. Pat. No. 4,410,742) deals with the preparation of organomagnesium alkoxides which are free from halogen and are soluble in hydrocarbons. This is effected by reacting hydrocarbon-soluble magnesium alkyls as such or complexed with, for example, aluminum trialkyls, with magnesium dialkoxides in a mol ratio of 1:1. The patent points out that magnesium dialkoxides, which are solid and can scarcely be brought into solution, dissolve rapidly when reacted with magnesium alkyls to form clear solutions in inert polar and non-polar, e.g., hydrocarbon solvents, to produce low-viscosity concentrated solutions. Mueller does not disclose the production of magnesium dialkoxides or alkylmagnesium alkoxides in which the alkoxy-to-alkyl ratios are substantially greater than 1, which have a particularly high solubility in hydrocarbon or chlorinated hydrocarbon solvents.
Ragazzini et al (U.S. Pat. No. 3,294,770) is directed to a process of polymerizing vinyl chloride (PVC) to produce PVC with certain improved properties. This is achieved by carrying out the polymerization of vinyl chloride, in bulk or mass, or in inert solvents, which may be saturated hydrocarbons or polar solvents, in the presence of a catalyst selected from the class consisting of mono- or dialcoholates of aluminum alkyls, tri-alcoholates of aluminum, alkyl magnesium alcoholates, and alcoholates of lithium. Among such catalysts disclosed in this patent are Al(C.sub.2 H.sub.5).sub.2 (OC.sub.4 H.sub.9).sub.2 ; (C.sub.2 H.sub.5)Al(OC.sub.4 H.sub.9).sub.2 ; LiOBu; and (C.sub.4 H.sub.9)Mg(OC.sub.3 H.sub.7), a butylmagnesium propoxide prepared by reacting dibutyl-magnesium with one molar equivalent of n-propyl alcohol. It may be noted that, in Example No. 14 of said patent, no hydrocarbon solvent is utilized in the preparation of the catalyst or in the preparation of PVC therewith. While this patent broadly encompasses certain alkylmagnesium alkoxides and certain magnesium dialkoxides, it has nothing to do with any concept or objective of producing certain magnesium dialkoxides which have materially enhanced solubility in hydrocarbon or chlorinated hydrocarbon solvents. Indeed, most of the catalysts of said patent are alkyl aluminum alkoxides or aluminum alkoxides, and some others are LiOBu and the aforementioned (C.sub.4 H.sub.9)Mg(OC.sub.3 H.sub.7).
Towers (U.S. Pat. No. 3,094,546) deals with processes for preparing, among other compounds, metal alkoxide compounds. Among such alkoxide compounds are magnesium methylate. Towers does not remotely deal with the production of magnesium dialkoxides in hydrocarbon or chlorinated hydrocarbon solvents, let alone any solution to the problem of producing particular types of magnesium dialkoxides having excellent solubility in hydrocarbon or chlorinated hydrocarbon solvents made in accordance with certain facets of the present invention.
It has also heretofore been known, as disclosed in European Patent Application (EPO) Publication No. 0 156 512 Al, to produce certain olefin polymerization titanium-containing catalysts by contacting an inert solvent (e.g., a hydrocarbon solvent)-soluble magnesium alkoxide with certain silicon compounds and an electron donor compound, the magnesium dialkoxides used in the preparation of said catalysts being represented by the formula Mg(OR)(OR.sup.1), where R and R.sup.1 are the same or different alkyl, cycloalkyl, aryl, alkenyl, or aralkyl groups. It is pointed out in said EPO publication that those magnesium dialkoxides having hydrocarbon groups with less than 7 carbon atoms are insoluble in inert solvents, such as hydrocarbon and chlorinated hydrocarbon solvents, and that it is, therefore, necessary that the hydrocarbon groups in the magnesium dialkoxides, used in the preparation of the aforementioned catalysts of this EPO Publication, should have a carbon number greater than 7 and side chains. Numerous examples of magnesium dialkoxides which contain a carbon number greater than 7 and which are stated to be useful in the preparation of said catalysts are given, illustrative of which are magnesium di-2-ethylhexyloxide, magnesium di-2 -methylhexyloxide, magnesium di-2-(methylethyl) pentyloxide; and, also, such magnesium dialkoxides as magnesium di-1-ethylhexyloxide, magnesium di-1-ethylpentyloxide, magnesium di-1-propylbutoxide, magnesium di-1-methylheptyloxide, magnesium di-4-methylcyclohexyloxide, and many others. Methods of preparation of said magnesium dialkoxides are also disclosed as, for instance, by reacting metallic magnesium or dihydrocarbyl magnesium with an alcohol represented by ROH or R'OH (where R and R' are the same as defined above); or, alternatively, by reacting a magnesium dialkoxide insoluble in an inert solvent with an alcohol having the same hydrocarbon group as the desired dialkoxide has.
With due regard for what has been noted above is stated in said EPO Publication with respect to the preparation and the manner of preparation of magnesium dialkoxides which are soluble in the aforementioned hydrocarbon or chlorinated hydrocarbon solvents, so far as I have been able to ascertain, based upon much experimental work, linear, unbranched secondary magnesium dialkoxides do not, in fact, generally speaking, form flowable, and particularly relatively readily flowable, clear solutions in hydrocarbon or chlorinated hydrocarbon solvents unless there is present in the preparation thereof, or added, aluminum compounds such as, by way of example, aluminum trialkyls exemplified by triethyl aluminum and triisobutyl aluminum; or aluminum trialkoxides exemplified by aluminum triethoxide and aluminum triisopropoxide. In other words, in the absence of such or other aluminum compounds, the magnesium dialkoxides, or purported magnesium dialkoxide compositions, are obtained in forms which are generally highly objectionable intractable solids or semi-solid gel-like compositions.
Thus, in connection with the foregoing, reference is first made to Example 1 on Page 15 of the aforesaid EPO Publication where the preparation of a colorless transparent viscous solution of the magnesium dialkoxide, specifically, magnesium di-2-ethylhexyloxide, is described. In the preparation of said magnesium dialkoxide, briefly summarized, to a solution of butylethyl magnesium in n-heptane (which butylethyl magnesium is a commercially produced composition designated as MAGALA BEM, a product of Texas Alkyls Co., Ltd. in U.S.) there is added, dropwise, a mixture of 2-ethylhexanol and n-heptane, with stirring, and then the resulting mixture is heated to 120.degree. C. and stirred at the reflux temperature of n-heptane for 1 hour to complete the reaction. It is well-known to those familiar with the art that BEM (which is an abbreviation for butylethyl magnesium), for which Texas Alkyls Co. issues a product data sheet in the U.S., which clearly shows the presence of 0.02 to 0.05 wt. % aluminum in product solutions containing 2.1 to 2.3 wt. % magnesium (the latter figure corresponding to 10 wt. % of BEM). A laboratory analytical report put out by Texas Alkyls Co. accompanying a pint bottle of the MALAGA BEM shows the presence of 0.05 wt. % of aluminum and 2.20 wt. % magnesium in the solution. It is clear, therefore, that, in Example 1 of said EPO Publication, the magnesium dialkoxide contained aluminum, and, to those skilled in the art, in the form of an organoaluminum compound. In this regard, it may additionally be pointed out that it is also generally known to the art that the addition of various organoaluminum compounds, such as trialkylaluminum compounds, to linear (unbranched) di-alkylmagnesium compounds such as, for example, n-butyethylmagnesium, di-n-hexylmagnesium, and di-n-butylmagnesium promotes or enhances the solubility of these dialkylmagnesium compounds in hydrocarbon or chlorinated hydrocarbon solvents and lowers the viscosity of such solutions sufficiently to allow them to be easily handled (as, for instance, by pumping) as shown, by way of illustration, in U.S. Pat. No. 3,737,393.
The foregoing situation, in relation to Example 1 of said EPO Publication, has the same applicability to Examples 10 to 12 of said EPO Publication, where the MAGALA BEM is shown to have been used in the preparation of magnesium dialkoxide heptane solutions of magnesium di-1-methylhexyloxide, magnesium di-1-methylheptyloxide, and magnesium di-1-dimethylpentyloxide (linear, unbranched secondary magnesium dialkoxides), that is, they contain aluminum compounds.
Experimental work conducted by me and/or under my direction using, in place of MAGALA BEM, dibutyl magnesium (DBM), specifically n-butyl-sec-butyl magnesium, a partially branched dialkylmagnesium) solutions in heptane, or other hydrocarbon or chlorinated hydrocarbon solvents, prepared by me or other chemists employed by the Assignee of the present application, and containing no aluminum compounds, when reacted with 2-heptanol to produce magnesium di-1-methylheptyloxide, resulted in the formation of an intractable solid gel. The said gel was able to be brought into solution by the addition of triisobutylaluminum plus some additional 2-heptanol or 2-octanol. This experiment was repeated with other linear, unbranched C.sub.5 -C.sub.10 secondary magnesium dialkoxides, such as magnesium di-1-ethylpentyloxide (magnesium bis-3-heptyloxide), magnesium di-1-ethylhexyloxide (magnesium bis-3-octyloxide), magnesium di-1-methylnonyloxide (magnesium bis-2-decyloxide), and magnesium di-1-n-propylheptyloxide (magnesium bis-4-decyloxide). In all cases, intractable solid gels were obtained in the absence of aluminum trialkoxides as generated by (a) addition of trialkylaluminum compounds to the precursor DBM prior to reaction with the corresponding alcohol or (b) by addition of trialkylaluminum compounds to the formed gels followed by additional corresponding alcohol.
With further regard to the aforesaid EPO Publication, in those Examples thereof for the preparation of magnesium dialkoxide solutions wherein no organolaluminum compounds are employed, namely Examples 2 and 3 (magnesium di-2-ethylhexyloxide), viscous solutions low in magnesium concentration (0.1-0.3 M) are produced. (These are examples of branched primary magnesium dialkoxides, rather than the unbranched secondary dialkoxides discussed above.) Such viscous, low concentration solutions have the twin disadvantages of being difficult to pump from one container to another and of requiring the uneconomical shipment of large quantities of solvent relative to the contained product therein.
It is in order to note that in appreciable numbers of cases, especially in the use of magnesium dialkoxide solutions to prepare catalysts for the polymerization of olefins, it is advantageous to have little or preferably no aluminum alkoxide present in the magnesium dialkoxide solutions used to generate the magnesium chloride carrier for the titanium-bearing polyolefin catalyst, as the resulting magnesium chloride crystallites are contaminated with aluminum chloride. On subsequent treatment of the resulting catalyst with aluminum alkyl co-catalyst, the occluded aluminum chloride can be leached out, thus causing degradation of the MgCl.sub.2 crystal lattice, leading to undesirable changes in the selectivity of the catalyst, and in some cases to a lower catalyst efficiency.
In order to demonstrate the facts in the relation to the absence of organolaluminum compounds on the nature of the magnesium dialkoxide compositions of the type made according to such Examples as 1 and 10 to 12 of the aforementioned EPO Publication, there is set forth below the results of some illustrative experiments which were carried out by me and/or under my direction: